Infante Carlos of Spain, also known as Charles of Spain (15 September 1607 – 30 July 1632) was infante of Spain, the second son of Philip III of Spain and Margaret of Austria. Charles was the younger brother of Philip IV and as long as the King remained childless was heir to the Spanish throne. Charles was never a friend of Philip's favourite and prime minister, the Count-Duke of Olivares, and though he was uninterested in politics, he was used by various nobles in attempts to overthrow Olivares. During his brother's severest illness, Charles was on the point of ascending the throne but Philip recovered and in 1629 finally fathered a son, Balthasar Charles. This dissipated Charles' political importance completely.

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